A TSP in Cell technique, i.e., a technique in which a touch screen panel (TSP) is integrated in a liquid crystal cell, refers to manufacturing a sensor of the TSP and its driving circuit on an array substrate using an array process. By integrating the TSP sensor in a cell of a liquid crystal display (LCD) panel (LCD Panel Cell), it is able to provide a light and thin product with diversified functions, and to effectively improve the reliability of the TSP.
Referring to FIG. 1, which shows an existing basic light-induced touch driving circuit, the sensor senses light using a photodiode D1 and generates a leakage current so as to detect a touch signal. A thin-film transistor (TFT) T1 serves as an amplification transistor so as to enhance outputting and driving capabilities of the touch driving circuit, thereby to enable a TSP external reading circuit to read a detection result accurately. This circuit is present in each pixel in the cell, wherein VINI represents an initial level, and OUTPUT represents a data reading line. Each row of pixels in the cell is provided with an initial signal line so as to drive the respective touch driving circuits through VINI, and each column of pixels is provided with a data reading line so as to read the touch signal through OUTPUT.
For an existing process, a circuit of the panel is manufactured using a low temperature poly-silicon (LTPS) technique. However, elements manufactured by this process are of non-uniform parameters, resulting in non-uniform level gains for the amplification transistors of the respective touch driving circuits as well as different touch signals amplified and outputted by the amplification transistors when the same touch is made. As a result, an error will occur when the touch signal is read.